Micropump with valve structure

Abstract

A micropump for pumping liquid from an entry channel to an exit channel is disclosed. The micropump is formed in a semiconductor substrate sealed by two glass substrates. The micropump includes first and second chambers and flow channel means coupled between the two chambers. The micropump also includes a valve coupled between the entry channel and the first chamber. The valve includes a flexible valve membrane positioned closer to a second side of the semiconductor substrate than to its first side for causing the valve to be or not to be in contact with the second side of the semiconductor substrate for closing or opening the valve on the glass substrate. Additionally, the micropump includes a diaphragm forming part of a flexible wall of the second chamber and positioned closer to the second side of the semiconductor substrate than to its first side. The diaphragm is responsive to external pressure for causing liquid to be pumped from the entry channel to the exit channel. Thus, the height of the valve is reduced, preventing deformation due to strength such as its own weight and may impact due to a dropping. As a result, the valve sealing is improve on the glass substrate. Therefore, the micropump can accurately discharge a small quantity of liquid.

What is claimed is: 
     
       1. A micropump formed in a silicon substrate sandwiched between two glass substrates, comprising: a diaphragm for pumping liquid;   a flow channel;   a valve, responsive to the diaphragm, for causing liquid to be pumped through the flow channel, the valve including a valve membrane; and   a preloading layer deposited on the valve, such that contact between the preloading layer and one of the glass substrates tightens the seal of the valve, the preloading layer comprising a high-polymer material having at least one of polyimide and polyamide.   
     
     
       2. The micropump of claim 1, wherein: the preloading layer is formed as a conical tip on the valve.   
     
     
       3. The micropump of claim 2, wherein: the conical tip has a width ≦500 microns and a height ≦5 microns.   
     
     
       4. A micropump for pumping liquid from an entry channel to an exit channel, the micropump formed in a semiconductor substrate disposed between two sealing substrates such that first and second sides of the semiconductor substrate are in contact with the sealing substrates, the micropump comprising: a first chamber;   valve means coupled between the entry channel and said first chamber, the valve means including a flexible valve membrane means positioned closer to the second side of the semiconductor substrate than to the first side of the semiconductor substrate for causing said valve means to be or not to be in contact with the sealing substrate contacting the second side of the semiconductor substrate for closing or opening said valve means;   a second chamber;   flow channel means coupled between said first chamber and said second chamber; and   diaphragm means forming part of a flexible wall of said second chamber and positioned closer to the second side of the semiconductor substrate than to the first side of the semiconductor substrate, said diaphragm responsive to external pressure for causing liquid to be pumped from the entry channel to the exit channel.   
     
     
       5. The micropump of claim 4, further comprising a preloading layer formed on said valve means for contacting with the sealing substrate contacting the second side of the semiconductor substrate. 
     
     
       6. The micropump of claim 5, wherein: the preloading layer comprises a nitride layer.   
     
     
       7. The micropump of claim 5 wherein said preloading layer comprises polyimide. 
     
     
       8. The micropump of claim 5 wherein said preloading layer comprises polyamide. 
     
     
       9. The micropump of claim 5 wherein said preloading layer comprises a silicon dioxide. 
     
     
       10. The micropump of claim 5 wherein said preloading layer comprises a high-polymer material. 
     
     
       11. The micropump of claim 10, said preloading layer is formed as a conical tip on said valve means. 
     
     
       12. The micropump of claim 11, wherein the conical tip has a width ≦500 microns and a height ≦5 microns. 
     
     
       13. The micropump of claim 10 further comprising a piezoelectric flexor means mounted on said diaphragm means for causing said diaphragm means to vibrate to pump liquid. 
     
     
       14. A micropump for pumping liquid from an entry channel to an exit channel, the micropump formed in a semiconductor substrate disposed between two sealing substrates such that first and second sides of the semiconductor substrate are in contact with the sealing substrates, the micropump comprising: a first chamber;   first valve means coupled between the entry channel and said first chamber, said first valve means including a flexible valve membrane means positioned closer to the second side of the semiconductor substrate than to the first side of the semiconductor substrate for causing said first valve means to be or not to be in contact with the sealing substrate contacting the second side of the semiconductor substrate for closing or opening said first valve means;   an second chamber;   a first flow channel coupled between said first chamber and said second chamber;   a third chamber;   a second flow channel coupled between said second chamber and said third chamber;   second valve means coupled between said third chamber and the exit channel, said second valve means including a flexible valve membrane means positioned closer to the second side of the semiconductor substrate than to the first side of the semiconductor substrate for causing said second valve means to be or not to be in contact with the sealing substrate contacting the second side of the semiconductor substrate for closing or opening said second valve means; and   diaphragm means forming part of a flexible wall of said second chamber and positioned closer to the second side of the semiconductor substrate than to the first side of the semiconductor substrate, said diaphragm means responsive to external pressure for causing liquid to be pumped from the entry channel to the exit channel.   
     
     
       15. The micropump of claim 14, further comprising a preloading layer formed on said first and second valve means for contacting with the sealing substrate contacting the second side of the semiconductor substrate. 
     
     
       16. The micropump of claim 15, wherein said preloading layer comprises polyimide. 
     
     
       17. The micropump of claim 15, wherein said preloading layer comprises polyamide. 
     
     
       18. The micropump of claim 15, wherein said preloading layer comprises a silicon dioxide. 
     
     
       19. The micropump of claim 15, wherein said preloading layer comprises a high-polymer material. 
     
     
       20. The micropump of claim 19, said preloading layer is formed as a conical tip on said first and valve means. 
     
     
       21. The micropump of claim 20 wherein the conical tip has a width ≦500 microns and a height ≦5 microns. 
     
     
       22. The micropump of claim 19 further comprising a piezoelectric flexor means mounted on said diaphragm means for causing said diaphragm means to vibrate to pump liquid.